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virgl: fix a sync issue in virgl_buffer_transfer_extend 

In virgl_buffer_transfer_extend, when no flush is needed, it tries
to extend a previously queued transfer instead if it can find one.
Comparing to virgl_resource_transfer_prepare, it fails to check if
the resource is busy.

The existence of a previously queued transfer normally implies that
the resource is not busy, maybe except for when the transfer is
PIPE_TRANSFER_UNSYNCHRONIZED.  Rather than burdening us with a
lengthy comment, and potential concerns over breaking it as the
transfer code evolves, this commit makes the valid_buffer_range
check the only condition to take the fast path.

In real world, we hit the fast path almost only because of the
valid_buffer_range check.  In micro benchmarks, the condition should
always be true, otherwise the benchmarks are not very representative
of meaningful workloads.  I think this fix is justified.

The recent change to PIPE_TRANSFER_MAP_DIRECTLY usage disables the
fast path.  This commit re-enables it as well.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
This commit is contained in:
Chia-I Wu 2019-07-16 16:48:03 -07:00
parent 324c20304e
commit d31d25f634
1 changed files with 15 additions and 62 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

77
src/gallium/drivers/virgl/virgl_resource.c
View File

@ -536,76 +536,29 @@ void virgl_init_screen_resource_functions(struct pipe_screen *screen)
screen->resource_destroy = u_resource_destroy_vtbl;
}
static bool virgl_buffer_transfer_extend(struct pipe_context *ctx,
struct pipe_resource *resource,
unsigned usage,
const struct pipe_box *box,
const void *data)
{
struct virgl_context *vctx = virgl_context(ctx);
struct virgl_resource *vbuf = virgl_resource(resource);
struct virgl_transfer dummy_trans = { 0 };
bool flush;
/*
* Attempts to short circuit the entire process of mapping and unmapping
* a resource if there is an existing transfer that can be extended.
* Pessimestically falls back if a flush is required.
*/
dummy_trans.base.resource = resource;
dummy_trans.hw_res = vbuf->hw_res;
dummy_trans.base.usage = usage;
dummy_trans.base.box = *box;
dummy_trans.base.stride = vbuf->metadata.stride[0];
dummy_trans.base.layer_stride = vbuf->metadata.layer_stride[0];
dummy_trans.offset = box->x;
flush = virgl_res_needs_flush(vctx, &dummy_trans);
if (flush && util_ranges_intersect(&vbuf->valid_buffer_range,
box->x, box->x + box->width))
return false;
if (!virgl_transfer_queue_extend_buffer(&vctx->queue,
vbuf->hw_res, box->x, box->width, data))
return false;
util_range_add(&vbuf->valid_buffer_range, box->x, box->x + box->width);
return true;
}
static void virgl_buffer_subdata(struct pipe_context *pipe,
struct pipe_resource *resource,
unsigned usage, unsigned offset,
unsigned size, const void *data)
{
struct pipe_transfer *transfer;
uint8_t *map;
struct pipe_box box;
struct virgl_context *vctx = virgl_context(pipe);
struct virgl_resource *vbuf = virgl_resource(resource);
assert(!(usage & PIPE_TRANSFER_READ));
/* the write flag is implicit by the nature of buffer_subdata */
usage |= PIPE_TRANSFER_WRITE;
if (!(usage & PIPE_TRANSFER_MAP_DIRECTLY)) {
if (offset == 0 && size == resource->width0)
usage |= PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE;
else
usage |= PIPE_TRANSFER_DISCARD_RANGE;
}
u_box_1d(offset, size, &box);
if (usage & PIPE_TRANSFER_DISCARD_RANGE &&
virgl_buffer_transfer_extend(pipe, resource, usage, &box, data))
/* We can try virgl_transfer_queue_extend_buffer when there is no
* flush/readback/wait required. Based on virgl_resource_transfer_prepare,
* the simplest way to make sure that is the case is to check the valid
* buffer range.
*/
if (!util_ranges_intersect(&vbuf->valid_buffer_range,
offset, offset + size) &&
likely(!(virgl_debug & VIRGL_DEBUG_XFER)) &&
virgl_transfer_queue_extend_buffer(&vctx->queue,
vbuf->hw_res, offset, size, data)) {
util_range_add(&vbuf->valid_buffer_range, offset, offset + size);
return;
map = pipe->transfer_map(pipe, resource, 0, usage, &box, &transfer);
if (map) {
memcpy(map, data, size);
pipe_transfer_unmap(pipe, transfer);
}
u_default_buffer_subdata(pipe, resource, usage, offset, size, data);
}
void virgl_init_context_resource_functions(struct pipe_context *ctx)